1993 ranger 4x4 STX

[Dumped14]

Cannot get computer to work plug code reader in and no codes 4.0will not fire even switched the computer with another working one still no fire replaced fuel pump and icm any one had this problem

 

[RonD]

Do a 50/50 test to see if you have spark
Pull off air tube on upper intake manifold
Open throttle and spray gasoline or Quick Start(ether) into the intake
Try to start engine
If it starts up but dies quickly then fuel is the problem
If it doesn't start then spark is the problem
50/50


1994 and earlier 4.0l Rangers have the computer(EEC) for Fuel injection and EDIS-6 module for Spark.

Both get power(12v) from the EEC Fuse(30amp) via EEC relay, both in engine fuse box.

When you turn on the key the EEC Relay should "click" closed and the CEL(check engine light) on the dash should come on, CEL means computer is powering up.

You should also hear a second "click" from the Fuel Pump Relay(in engine fuse box), and then a "HUMMMM" from the fuel pump running for 2 seconds, it will run 2 seconds only, but it will run for those 2 seconds each time key is turned on.

On the lower front of the engine next to the Crank shaft pulley is the CKP(crank position) sensor.
This is the Big Kahuna of sensors.
When starter motor turns the engine/crank, the CKP sensor will send pulses to the EDIS-6 module, these pulses time the spark.
EDIS-6 module sends these timing pulses to the computer, this times the fuel injectors
So no CKP pulse means no spark and no fuel, important sensor

 

[Dumped14]

I tried the 50/50 test and still no fire. When it guit the engine light flashed a few times and finally shut down. The check engine light does not come on at all when I turn key on. Will the cop cause this problem also?

 

[RonD]

COP?
Coil on Plug, not used in 1993 Rangers

If CEL is not coming on then computer is not coming on.
Check EEC Fuse and EEC Relay first

The coil pack on the 4.0l will have a 4 wire connector, disconnect it.
There will be 1 Red wire, that wire should have 12volts when key is on.

This 12volts comes from EEC Fuse and EEC relay as well
EEC fuse powers coil pack, EDIS module, fuel injectors, MAF and EEC(computer), so blown EEC Fuse would cause a no spark, as would a bad EEC Relay not passing power

When you turn on the key does the Battery Light come on?
That means ignition switch is working

 

[Dumped14]

Yes battery light comes on and I meant crank shaft position sensor not cop sorry auto correct got me again

 

[Dumped14]

COP?
Coil on Plug, not used in 1993 Rangers

If CEL is not coming on then computer is not coming on.
Check EEC Fuse and EEC Relay first

The coil pack on the 4.0l will have a 4 wire connector, disconnect it.
There will be 1 Red wire, that wire should have 12volts when key is on.

This 12volts comes from EEC Fuse and EEC relay as well
EEC fuse powers coil pack, EDIS module, fuel injectors, MAF and EEC(computer), so blown EEC Fuse would cause a no spark, as would a bad EEC Relay not passing power

When you turn on the key does the Battery Light come on?
That means ignition switch is working

Battery light does come on have power to cool pack still no power to computer relay and fuse are good

 

[RonD]

Pull out the EEC relay
With Key OFF, test each slot in the Relay base/socket, one should have 12volts, thats the power from the EEC Fuse.
Now turn Key to ON(RUN), test slots again, there should now be a 2nd slot with 12volts, that's from the ignition switch.

This is a diagram of a standard automotive 5 pin relay: http://www.enginebasics.com/Advanced Engine Tuning/Images/Relay Picture.jpg

Yes they do number them oddly
4 pin relay won't have 87A, same pin lay out just no 87A pin

85 and 86 are used to activate(close) the relay
There is no polarity for 85 or 86, if 85 has 12v AND 86 is Grounded then relay will close, and visa versa, if 86 has 12v and 85 is grounded relay will close.
If there is no 12v or no ground then relay will not close.

30 and 87 is where the "power" from the fuse passes thru when relay is closed.
When voltage passes thru the Coil(85 and 86) it becomes a magnet and pulls down the metal "arm" in the relay, this connects pins 30 and 87 together.

Pin 30 is usually connected to the fuse and 87 to the device being powered(load), in this case the EEC(computer).
But there is no reason that can not be reversed, 87 could be Fuse power and 30 the EEC.

If you find 12v at slot 85 or 86 confirm the "other one" is a good Ground.
If no 12v at 85 or 86 then check relay base the wires can and do corrode.

 

[Dumped14]

Pull out the EEC relay
With Key OFF, test each slot in the Relay base/socket, one should have 12volts, thats the power from the EEC Fuse.
Now turn Key to ON(RUN), test slots again, there should now be a 2nd slot with 12volts, that's from the ignition switch.

This is a diagram of a standard automotive 5 pin relay: http://www.enginebasics.com/Advanced Engine Tuning/Images/Relay Picture.jpg

Yes they do number them oddly
4 pin relay won't have 87A, same pin lay out just no 87A pin

85 and 86 are used to activate(close) the relay
There is no polarity for 85 or 86, if 85 has 12v AND 86 is Grounded then relay will close, and visa versa, if 86 has 12v and 85 is grounded relay will close.
If there is no 12v or no ground then relay will not close.

30 and 87 is where the "power" from the fuse passes thru when relay is closed.
When voltage passes thru the Coil(85 and 86) it becomes a magnet and pulls down the metal "arm" in the relay, this connects pins 30 and 87 together.

Pin 30 is usually connected to the fuse and 87 to the device being powered(load), in this case the EEC(computer).
But there is no reason that can not be reversed, 87 could be Fuse power and 30 the EEC.

If you find 12v at slot 85 or 86 confirm the "other one" is a good Ground.
If no 12v at 85 or 86 then check relay base the wires can and do corrode.

Thanks for previous postI pulled the ecc relay and only had power on one side with key on I I tested the 30amp fuse and only 1 side had power. I replaced the fuse and truck started but only ran a few minutes and quit again the fuse had blown again. It had power on one side again. Any thoughts what might be blowing the fuse I'm looking for a short or ground